Method and device for cutting film used to wrap groups of products

ABSTRACT

A device and method for cutting and re-attaching film for wrapping groups of palletized products are provided. Following the wrapping of a pack, the width of the section of film extending between a reel and the pack is reduced, using an assembly that defines a band of film with minimum width that, at least at one point, is coplanar with a rotating platform. The section of film is then gripped by a gripper and cutting unit. The gripper and cutting unit are attached to the outer edge of the platform. The section of film is then cut by the cutting unit following rotation of the platform.

TECHNICAL FIELD

The present invention relates to a method and the relative device forcutting and re-attaching film used to wrap groups of products. Inparticular this unit can be applied to machines for the semi-automaticwrapping of packs of products arranged on pallets for transportation ofthe packs.

BACKGROUND ART

In the sector for the design and construction of machines for wrappingpacks of products, manufacturers have, over time, used two differentconstruction philosophies, which have led to the definition of two typesof machines, respectively automatic and semi-automatic.

These two types originate from a similar basic structure which comprisesa support platform for the pallet upon which the group of products to bewrapped rests, and a frame, at the side of the platform, upon which areel of film for wrapping the group of products is positioned.

In the case of automatic machines, there are solutions which envisage arotating platform and in which the reel only moves vertically up anddown in order to unwind the film along the group of products, orsolutions with a fixed platform and a reel which moves vertically and issupported by an arm which rotates about the group of products.

In semi-automatic machines, the first type of system described above forautomatic machines is normally used, that is to say, with the rotatingplatform and a reel which moves in both directions along a verticalaxis; these two machines are basically differentiated by the fact thatthe automatic machines can carry out a series of cycle start and endoperations (for example, positioning the free edge of the film near thepack, cutting the film upon completion of wrapping and sealing the edgeon the pack thus defined, etc.) using automatic devices and without thedirect action of operators on the machine; in contrast, in the case ofsemi-automatic machines, operators are required in order to carry outsaid operations.

Obviously, these differences mean that the automatic machines are veryexpensive, used only for high productivity and are top of the range,whilst the semi-automatic machines are economically better suited tocompanies with medium-small production levels.

SUMMARY OF THE INVENTION

In order to bring the two types of machines closer together, theApplicant has designed a method for cutting the film and the relativedevice which makes the cut and re-attaches the film for semi-automaticmachines, with which it is possible to automate the film cutting andre-attachment operation without significantly affecting the cost of themachine and leaving the structure and functions of the currentsemi-automatic machine unchanged.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical features of the present invention, in accordance with theafore-mentioned aims, are described in the claims herein, and theadvantages of the invention are more clearly described in the detaileddescription below with reference to the accompanying drawings, whichillustrate a preferred embodiment, and in which:

FIG. 1 is a schematic top plan view, with some parts cut away to betterillustrate others, of a machine for wrapping groups of products in aplastic film, equipped with the device which carries out the cuttingaccording to the present invention;

FIG. 2 is a schematic side view of the machine illustrated in FIG. 1,with some parts cut away to better illustrate others;

FIG. 3 is a top plan view of a scaled-up detail from FIG. 1,illustrating a film gripper and cutting unit during a stage of themethod according to the present invention;

FIGS. 4 and 5 are schematic side views, partially shown incross-section, of corresponding and different embodiments of the gripperand cutting unit illustrated in FIG. 3;

FIGS. 6 and 7 are schematic front views df a stage of the methoddisclosed, in particular a stage in which the width of the film isreduced;

FIGS. 8 and 9 are schematic top plan views of two stages of the methoddisclosed, in particular the stage in which the film is cut and thestage in which the edge of the film cut is attached to another pack tobe wrapped;

FIGS. 10 and 11 are respectively a schematic top plan view and aschematic side view partially shown in cross-section of a furtherembodiment of the gripper and cutting unit according to the presentinvention.

FIGS. 12, 13 and 14 illustrate another embodiment of the gripper andcutting unit according to the present invention, in three differentoperating positions, all being side views from N relative to thesuccessive FIGS. 17, 18 and 19 and with some parts shown incross-section and other parts cut away to better illustrate technicaldetails;

FIG. 15 is a top plan view of the gripper and cutting unit relative toFIGS. 12 and 14, with some parts cut away to better illustrate others;

FIG. 16 is an exploded side view of the parts of which the gripper andcutting unit in FIGS. 12 and 14 consists;

FIGS. 17, 18 and 19 are top plan views of a part of the machine forwrapping groups of products equipped with the unit illustrated in FIGS.12 and 14 in three different operating configurations and with a furtherdevice for heating and detaching the final section of the film, withsome parts cut away to better illustrate others.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the accompanying drawings, in particular FIGS. 1 and2, the method disclosed is actuated by cutting a plastic film 1 used towrap palletised groups of products.

These groups of products are wrapped using a film with width L so thatthey form a pack 2 with the shape of a parallelepiped and preset heightH.

The stages which allow this wrapping envisage: positioning the pack 2 ona wrapping platform 3; fixing a free edge of the film 1 at a point onthe platform 3 near the pack 2 (or directly on the pack 2, but neitherconfiguration is illustrated, since they are of the known type), thenwrapping the film 1 around the pack 2 by rotating the platform 3 about avertical axis Z.

The film 1 is unwound from a reel 4, which rotates idly about itsvertical axis Z1 and moves vertically up and down between two endpositions, one being the lowest position (see dashed line in FIG. 2), inwhich the reel 4 is near the platform 3, and the other being the highestposition (see continuos line in FIG. 2), in which the reel 4 isdistanced from the platform 3 at a height H1 approximately the same asthe height of the pack 2.

When the reel 4 is in the lowered position, that is to say, whenwrapping of the pack 2 has been completed, the width L of the section offilm 1 between the reel 4 and the pack 2 is reduced (see also FIGS. 6and 7), by relative means 5 (described in the text below), until a bandC of film 1 with minimum width is defined which, at least at one point,is substantially coplanar with the platform 3 which is still rotating.

Subsequently, this section of the band C of film 1 is first gripped by acutting unit 6 (see FIG. 3) attached to the outer edge 3a of theplatform 3, then cut by said unit 6 following rotation of the platform3.

The situation just described is illustrated in FIG. 8, where the film 1is divided into two sections, labelled 1a and 1b: the part of film 1b isremoved when the operator picks up the pack 2, whilst the cut edge laconnected to the reel 4 is first held by the gripper and cutting unit 6during positioning of a new pack 2 to be wrapped and for a subsequentrotation of the platform 3 (see in particular FIG. 9), so as to obtainautomatic re-attachment of the film to the new pack 2 to be wrapped.Once re-attached, this edge 1a of the film is removed when the edge isintercepted by relative first fixed cam means 7 located near theplatform 3.

As an alternative to the above, see in particular FIG. 19, againfollowing the stage at which the film 1 is gripped and cut, it ispossible to carry out a further stage for removal of the cut edge orsection 1a of film 1 by means of a flow of hot air generated by relativemeans 162 (more clearly described later in this text): this flow of hotair acts directly upon the edge la of the film 1 between the pack 2 andthe gripper and cutting unit 6, softening the edge, so that the sectionthen sticks to the pack 2, pushed towards the latter by the air flow.

The device which allows actuation of the above-mentioned method isapplied to machines for wrapping said groups of palletised products withthe plastic film 1.

Obviously, these machines comprise said platform 3, which rotates in adirection of wrapping A, the reel 4 which can rotate about its verticalaxis Z1 and is supported by a frame 8 located at the side of theplatform 3 and equipped with a guide 8g, designed to allow the reel 4 toslide vertically up and down between the above-mentioned end positions.

As already indicated, means 5 are envisaged to allow a reduction in thewidth L of the section of film 1 extending from the reel 4 to the pack2, so as to define the band C of said section near the surface of theplatform 3. More precisely (see FIGS. 1, 2, 6 and 7), these means 5 forreducing the width of the band C are attached to the above-mentionedframe 8, partially between the reel 4 and the platform 3 to interceptthe section of film 1, and mobile along a vertical axis Z2 parallel withthe vertical axis Z1 of the reel 4 and partially synchronised with saidreel.

Said means 5 comprise a rod 9 positioned at the side of the reel 4 andpivoting at one end on the frame 8; at its other end, this rod 9 has anidle roller 9r which extends transversally relative to the section offilm 1 stretching from the reel 4 to the pack 2. The rod 9 is alsocontrolled by a guide pin 10 which is moved vertically by a chain 11connected to the single drive means 11m of the pin 10 and reel 4.

During normal wrapping, the upstroke and downstroke of the pin 10 allowsthe reel 4 to be moved and, subsequently, the rod 9 to be angled betweentwo end positions, one being the raised non-operating position, in whichthe rod 9 is almost vertical (see dashed line in FIG. 6), and a loweredoperating position, in which the rod 9 is horizontal (see FIG. 7 andarrow F1) at a height lower than that of the reel 4 in its loweredposition: in this way, the width of the film 1 is reduced until the bandC configuration is obtained.

More precisely, the pin 10 is integral with the chain 11 and, by meansof its contact with a bracket 10m integral with a weight 10z, allows thereel 4 to be raised, whilst the weight 10z allows constant loweringduring the pin 10 downstroke.

When the reel 4 reaches the lowest position, a limit switch 10c locksthe weight 10z and, therefore, also the reel, whilst the pin 10continues its descent, pulled by the chain 11, and makes contact withthe rod 9, continuing to push the latter downwards until it reaches thepreset position.

Following the above-mentioned stages in which the film is cut and theedge la attached to the new pack 2 to be wrapped, the chain 11 invertsits movement, allowing the pin 10 to rise again, immediately followed bythe rod 9, partly thanks to a return spring 9m connected to thestructure 8 and the rod, then by the reel 4 so as to begin a new cycle.

The above-mentioned gripper and cutting unit 6 for the band C is, asalready indicated, attached to the edge 3a of the platform 3, so that itis better able to intercept and cut the band C during the wrappingrotation of the platform 3.

More precisely, this cutting unit 6 comprises (see also FIGS. 3, 4 and5) a plate 12 fixed to the surface of the platform 3 and having a freeend 12a tapered to define a guide zone for the band-shaped section Cwhich can be inserted in and held by the plate 12 and a blade 13 housedinside the plate 12 and designed to allow cutting of the band-shapedsection during rotation of the platform 3.

As can be observed again in FIGS. 3, 4 and 5, one end of the plate 12 isattached to the platform 3 also by spring means 12m, which allow both agiven flexibility at the other end, designed to intercept the band C,and the return and sustained contact of said end with the platform 3during the latter's normal rotation. As already indicated, after theband C of film 1 has been cut, the section of film 1 remaining beneaththe plate 12 and attached to the reel 4 must be removed during rotationof the platform 3; the above-mentioned first fixed cam means 7, locatednear the platform 3, are envisaged for this purpose.

The embodiments relative to the type of blade 13 are illustrated in.FIGS. 4 and 5. In FIG. 4 the blade 13 is fixed inside the plate 12, thatis to say, one end is rigidly attached to the plate 12, and it isparallel with the platform 3, so that the platform acts as the stopplane for cutting the band C.

In FIG. 5 the blade 13 pivots, at point B, inside the plate 12 andremains parallel with the platform 3 when the band C of film 1 is cut,as in the previous embodiment. In this embodiment there are second cammeans 18, comprising an angled table 16 located below the platform 3 anddesigned to intercept a vertical lever 17 integral with the blade 13when the platform 3 rotates: when the angled table 16 intercepts thelever 17, it allows raising to obtain film 1 cutting following theraising of the blade 13 (see arrow F in FIG. 5) and its returndownstroke to the position parallel with the platform 3. The blade 13 isbrought to the latter position, for example, by the action of springmeans 18 located on a pivot pin 13p for the blade 13.

In both of the above-mentioned embodiments, said first cam means 7comprise a pin 15 in the shape of an upturned "L" projecting above theplatform 3, upstream of the reel 4 as regards the direction of wrappingA, and designed to intercept the edge of the film 1 already cut duringthe rotation following the cut, since the plate 12 pulls the edge of thefilm 1 along the edge 3a of the platform 3 to re-attach the film 1 tothe new pack 2 to be wrapped.

In FIGS. 10 and 11, the validity of the embodiment described isconfirmed by observing a further embodiment of the gripper and cuttingunit 6 for the film 1.

In this specific embodiment, said gripper and cutting unit 6 is attachedto the edge 3a of the platform 3 and comprises a plate 100 pivoting, atpoint D, on the upper surface of the platform 3.

The plate 100 has a shaped free end 100a, angled upwards, which definesa guide zone for the band-shaped section C which is inserted in theplate 100 and held by a blade 101 fixed perpendicular to the band C andinside the plate 12.

The blade 101, with a cutting portion 103 positioned vertically andtowards the outside of the platform 3, cuts the band-shaped section Cresting on the blade by means of drive means 102 which move the plate100 between a cutting position, in which it cuts the film 1 inserted andin which the plate 100 is turned towards the outside (see arrow F2 inFIG. 10), and a home position and/or position in which it holds the cutedge 1a of the film 1, in which the plate 100 is housed inside theplatform 3.

More precisely, the plate 100 drive means 102 comprise a cam profile 104defined by a pair of fixed walls 105 and 106 below the platform 3 which,when the platform 3 rotates, are intercepted by a first vertical camfollower pin 107 fixed inside the plate 100, and located upstream of theblade 101 relative to the direction of rotation A of the platform 3,allowing the above-mentioned cutting position. The blade 101 and pin 107project from the bottom of the platform 3 thanks to a through-hole 110in the platform.

To make the plate 100 return to the home position and/or holdingposition, there are spring means 108, with one end connected to theplate 100 and the other fixed to the platform 3; the platform 3 stablereturn position is given by a second vertical, end of stroke pin 109,again fixed to the platform 3.

This embodiment allows said release of the section la of film 1 cut fromthe plate 100 without the aid of the above-mentioned cam means 7 since,during the rotation following film 1 cutting, the rotation of the plate100 allows the edge to exit the plate thanks to the fact that the filmslide over the plate and the edge la already moved to the outer end ofthe plate 100 during the previous, cutting stage.

FIGS. 12 to 19 illustrate another embodiment of the above-mentionedgripper and cutting unit 6 for the band C of film 1. This unit 6 isattached to and located at the upper surface of the platform 3 (that isto say, partially inside the platform), which has a special through-hole150 in its surface.

This unit 6 comprises (see in particular FIGS. 15 and 16) a gripper 151,pivoting by its arm 151b, at point E, on the platform 3 and with anoperating end 152 which lies opposite and operates with a correspondingcutting portion 153 of a blade 154, pivoting by its arm 154b, at pointM, on the platform 3. In addition to these two elements, there is aframe 170 fixed to the platform 3 and designed to cover the edge of saidhole 150. Said frame also has a serrated contact profile 171 near to thezone in which the gripper 151 and blade 154 operate.

The gripper 151 and blade 154 are driven by first and second cam means155 and 156, allowing them to move independently but in a coordinatedmanner, again during rotation of the platform 3 in direction A, designedto allow respectively the interception, holding and cutting of a sectionof the band C as described for the previous embodiments.

More precisely, the above-mentioned first cam means 155 comprise a firstfixed wall 157, located below the platform 3, which extends in the shapeof an arc and has a substantially trapezoidal profile, designed to beintercepted by a first cam follower roller 158, attached in such a waythat it can rotate at an intermediate point of the arm 151b of thegripper 151, that is to say, between the pivot point E and the operatingend 152.

This configuration allows the gripper to be moved between severalpositions: a non-operating position, in which the gripper 151 issubstantially parallel with the platform 3 (see FIGS. 12 and 17); and anoperating gripping position, in which the gripper 151 is raised andangled relative to the platform 3, so that it intercepts the section ofband C created by the width reduction means 5 (see arrow F151 in FIG. 13and the straight section of the wall 157, also visible in FIG. 18);finally, an operating cutting position, in which the gripper 151 isagain parallel with the platform 3, allowing cutting of the section ofband C in co-operation with the blade 154 (see arrow FISla in FIG. 14and FIG. 19).

Again as can be observed in FIGS. 12 to 16, the gripper 151 have springmeans 161 which operate between the end of the gripper 151 opposite theoperating end 152 and the platform 3: this is a leaf spring 161supported by a bracket 161m attached to the platform 3 and designed tohold or return the gripper 151 in the lowered, non-operating position,keeping it there when not intercepted by the above-mentioned cam means155.

The blade 154 is moved by the above-mentioned second cam means 156,which comprise a second fixed wall 159 which extends in the shape of anarc, located beside the wall 157, and having a convex profile designedto be intercepted by a second cam follower roller 160 attached in such away that it can rotate to the arm 154b of the blade 154, so that itallows the blade to be moved between two end positions: a lowerednon-operating position, in which the blade 154 is angled and below theplatform 3 (see FIGS. 12 and 13), and a raised operating position, inwhich the blade 154 is parallel with the platform 3, with at least thecutting portion 153 above the platform to intercept and cut the sectionof the band C of film 1 simultaneous with the lowering of the gripper151 (see FIG. 14 and arrow F154 and FIG. 19). Thus, when the gripper 151is lowered and the blade 154 is raised, the section la of the band C iscut and locked.

When the platform is stationary (see again FIG. 19) and unit 6 is in theabove-mentioned configuration, said heating means 162 for the section 1aof the band C can operate directly on the band, allowing the section ofband C to be removed from the gripper and cutting unit 6 when said unitis activated: in this way, the section la is both removed from the unit6 and stuck to the side of the pack 2 located near the section.

More precisely, these heating means 162 comprise a fan unit 163 forheated air (of the known type, therefore illustrated only schematically)located below the platform 3 and which, upon completion of wrapping, canbe positioned opposite a through-hole 164 in the platform 3 near thegripper and cutting unit 6: this hole 164 may be shaped so as to directthe flow F164 of hot air onto an area of film 1 sufficient tosimultaneously soften the film and transfer it towards the pack 2,allowing it to stick to the latter.

This method and the relative device, therefore, allow theabove-mentioned objects to be achieved: the machine is not excessivelymodified compared with the known embodiment, thus maintaining a highlevel of reliability and practicality; the application of the widthreduction, gripper and cutting units does not lead to an excessiveincrease in the cost of the machine, but allows the automation of twostages (film cutting and re-attachment) until now effected manually.

The present invention may be subject to numerous modifications andvariations, all encompassed by the original design concept. Moreover,all components may be replaced with technically equivalent parts

What is claimed is:
 1. A device for cutting a plastic film (1) withwidth (L), used to wrap groups of palletized products in machinescomprising:a platform (3) rotating about a first vertical axis (Z) in adirection of wrapping (A) and supporting on a surface thereof a group ofproducts to be wrapped to form a pack (2), by said rotation of theplatform (3), with the film (1), wherein a free edge of the film isattached to the platform (3); a reel (4) supported for rotation about asecond vertical axis (Z1), said reel holding film that can be unwoundtherefrom and being supported by a frame (8) located adjacent theplatform (3) and allowing the reel (4) to be moved vertically up anddown, during said wrapping, between two end positions, one of said endpositions being the lowest, in which the reel (4) is adjacent theplatform (3), and the other of said end positions being the highest, inwhich the reel (4) is distanced from the platform (3) at a height (H1)approximately the same as the height (H) of the pack (2); means (5) forreducing the width (L) of a section of film (1) extending from the reel(4) to the pack (2), thereby defining a band (C) of the section adjacentthe surface of the platform (3); and, a gripper and cutting unit (6) forthe band shaped section (C), said gripper and cutting unit attached tothe platform (3) and intercepting and cutting the band (C) when theplatform (3) performs a wrapping rotation, wherein the means (5) forreducing the width of the band (C) of film (1) are attached to the frame(8), between the reel (4) and platform (3), and movable along a thirdvertical axis (Z2) parallel with the second vertical axis (Z1) of thereel (4) and partially synchronized with the reel, said width reductionmeans (5) comprising: a rod (9), pivoting at one end on the frame (8)and including an idle roller (9r) for contact with the film (1) andextending transversely relative to the section of film (1), said rod (9)being controlled by a guide pin (10), the latter being vertically mobileby means of a motor-powered chain (11) also acting upon the reel (4),said pin (10) angling the rod (9) between two end positions, one being araised, non-operating position, in which the rod (9) is distanced fromthe film (1), and the other being a lowered, operating position, inwhich the rod (9) is horizontal and at a height lower than the height ofthe reel (4) in its lowered position, allowing the roller (9r) to reducethe width of the band (C).
 2. The device according to claim 1, whereinthe gripper and cutting unit (6) is attached to the edge (3a) of theplatform (3) and comprises a plate (12), said plate being fixed to thesurface of the platform (3) and having a free end (12a) tapered todefine a guide zone for the band-shaped section (C), whereby saidband-shaped section is inserted and held between the plate (12) and ablade (13), said blade being housed inside the plate (12) and designedto cut the band-shaped section.
 3. The device according to claim 2,wherein the blade (13) is fixed inside the plate (12) and positionedparallel with the platform (3).
 4. The device according to claim 2,wherein the blade (13) pivots, at a point (B), inside the plate (12) andwherein the blade is positioned parallel with the platform (3) when theband (C) of film (1) is cut; said device further comprising:means (16,18) operating on the blade (13) for raising the blade and returning theblade to a position parallel with the platform (3).
 5. The deviceaccording to claim 4, wherein the blade operating means (16)comprise:second cam means, comprising an angled table (16), beinglocated below the platform (3) and designed to intercept a verticallever (17) integral with the blade (13), when the platform (3) rotates;and, spring means (18) for returning the blade to a position parallelwith the platform (3).
 6. The device according to claim 1, furthercomprising:first fixed cam means (7) located adjacent the platform (3)and allowing removal of an edge (1a) of the cut film (1) extending fromthe gripper and cutting unit (6) to the reel (4) when the platform (3)performs a subsequent rotation.
 7. The device according to claim 6,wherein the first cam means (7) comprises a pin (15) in the shape of anupturned "L" projecting above the platform (3) and being designed tointercept the edge (1a) of the cut film (1).
 8. The device according toclaim 1, wherein the gripper and cutting unit (6) is attached to theedge (3a) of the platform (3) and comprises a plate (100), said platepivoting at point (D) on the surface of the platform (3) and having afree end (10a) shaped to form a guide zone for the band-shaped section(C), wherein said band-shaped section is selectively insertable and heldbetween a blade (101) and the plate; said blade (101) being fixed insidethe plate (100) and perpendicular to the band (C) and allowing theband-shaped section (C) to be cut by means (102) which act upon theplate (100), said means allowing the plate to be moved between aposition for cutting the inserted film (1), in which the plate (100) isturned towards the outside, and a home position, or position for holdingan edge (1a) of the film (1), in which the plate (100) is housed insidethe platform (3).
 9. The device according to claim 8, wherein the blade(101) has a cutting portion (103) positioned vertically and directedtowards the outside of the platform (3).
 10. The device according toclaim 8, wherein the drive means (102) for the plate (100) comprise:acam profile (104), being defined by a pair of fixed walls (105, 106)located below the platform (3) and being intercepted, when the platform(3) rotates, by a first vertical cam follower pin (107) fixed to fixedto the plate (100), being upstream of the blade (101) relative to thedirection of rotation (A) of the platform (3), allowing the cuttingposition to be achieved; and, spring means (108) operating upon theplate (100) and fixed to the platform (3), and allowing the plate toreturn to the home position in co-operation with a second, end of strokepin (109), the latter being fixed to the platform (3).
 11. A device forcutting a plastic film (1) with width (L), used to wrap groups ofpalletized products in machines comprising:a platform (3) rotating abouta first vertical axis (Z) in a direction of wrapping (A) and supportingon a surface thereof a group of products to be wrapped to form a pack(2), by said rotation of the platform (3), with the film (1), wherein afree edge of the film is attached to the platform (3); a reel (4)supported for rotation about a second vertical axis (Z1), said reelholding film that can be unwound therefrom and being supported by aframe (8) located adjacent the platform (3) and allowing the reel (4) tobe moved vertically up and down, during said wrapping, between two endpositions, one of said end positions being the lowest, in which the reel(4) is adjacent the platform (3), and the other of said end positionsbeing the highest, in which the reel (4) is distanced from the platform(3) at a height (H1) approximately the same as the height (H) of thepack (2); means (5) for reducing the width (L) of a section of film (1)extending from the reel (4) to the pack (2), thereby defining a band (C)of the section adjacent the surface of the platform (3); and, a gripperand cutting unit (6) for the band shaped section (C), said gripper andcutting unit attached to the platform (3) and intercepting and cuttingthe band (C) when the platform (3) performs a wrapping rotation, saidgripper and cutting unit (6) attached to and located at the uppersurface of the platform (3), there being a through-hole (150) in theplatform, said gripper and cutting unit (6) comprising a gripper (151),pivoting at point (E) on the platform (3) and having an operating end(152) opposite and co-operating with a corresponding cutting portion(153) of a blade (154), the latter pivoting at point (M) on the platform(3); first cam means (155) and second cam means (156) operating upon thegripper (151) and on the blade (154), respectively, allowing theirindependent and coordinated movement during rotation of the platform(3), allowing a section of the band (C) to be intercepted, held and thencut.
 12. The device according to claim 11, wherein the first cam means(155) comprise a first fixed wall (157), being positioned below theplatform (3) and extending in the shape of an arc, with a substantiallytrapezoidal profile, and intercepted by a first cam follower roller(158), the roller rotatable attached to an intermediate point of thegripper (151) between the pivot point (E) and the operating end (152),allowing the gripper to be moved between several positions, at least onebeing a non-operating position, in which the gripper (151) issubstantially parallel with the platform (3), an operating grippingposition, in which the gripper (151) is raised and angled relative tothe platform (3)so as to intercept the section of band (C), and anoperating cutting position, in which the gripper (151) is parallel withthe platform (3), allowing cutting of the band (C) in cooperation withthe blade (154).
 13. The device according to claim 12, wherein that thegripper (151) comprises spring means (161) operating between the end ofthe gripper (151) opposite the operating end (152) and the platform (3),said siring means (161) holding the gripper (151) in and return it tothe lowered non-operating position.
 14. The device according to claim11, wherein the second cam means (156) comprise a second fixed wall(159), extending in the shape of an arc, with a convex profile, beingdesigned to intercept a second cam follower roller (160), the rollerbeing rotatable attached to the blade (154), thus allowing the blade tobe moved between two end positions, one of said end positions being alowered non-operating position, in which the blade (154) is angled andbelow the platform (3), the other of said end positions being a raisedoperating position, in which the blade (154) is parallel with theplatform (3) and with at least the cutting portion (153) above theplatform so as to intercept the section of the band (C) of film.
 15. Thedevice according to claim 11, wherein that the gripper (151) comprisesspring means (161) operating between the end of the gripper (151)opposite the operating end (152) and the platform (3), said spring means(161) holding the gripper (151) in and return it to the lowerednon-operating position.